Turbine

ABSTRACT

A turbine includes a sealing element with a receiving area for sealing the guide blade vanes which are adjacent to each other in the peripheral direction of the turbine. The foot plates of the guide blade vanes extend into the receiving area. The edge area of the foot plates does not have to be reinforced compared to a conventional seal, which enables the entire foot plate to be cooled homogeneously. A closed cooling system can therefore be used for cooling, especially with steam.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/EP01/02095 which has an Internationalfiling date of Feb. 23, 2001, which designated the United States ofAmerica and which claims priority on German Patent Application number EP00104345.4 filed Mar. 2, 2000, the entire contents of which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

The invention generally relates to a turbine, in particular a gasturbine.

BACKGROUND OF THE INVENTION

In a turbine, in particular in a gas turbine of a turbo set of a powerstation for energy generation, a hot gas is led through the turbine. Aresult is that a shaft having moving blades arranged on it is driven.This shaft is connected, as a rule, to a generator for the generation ofenergy. The moving blades extend radially outward. Stationary guidevanes are arranged in the opposite direction, that is to say radiallyfrom the outside inward. As seen in the longitudinal direction of theturbine, the guide vanes and the moving blades engage one into the otherin a tooth-like manner.

The turbine, as a rule, has a plurality of turbine stages, a guide vanering being arranged in each stage. Thus, a plurality of the guide vanesare arranged next to one another in the circumferential direction of theturbine. The individual guide vane rings are arranged successively inthe axial direction. The flow path of the hot gas through the turbine isdesignated hereafter as the gas space.

The guide vanes each include a vane leaf which extends radially into thegas space and is attached to a foot plate, via which the guide vane isfastened to what is known as a guide vane carrier. The individual footplates of the guide vanes form an essentially closed surface andoutwardly delimit the gas space. In order to achieve as small leakagegaps as possible between the individual foot plates, seals are provided,as a rule, between the individual foot plates.

In a conventional seal variant, the foot plate edge region is madethickened, particularly in the case of foot plates adjacent to oneanother in the circumferential direction, an end-face groove beingworked into the thickening. For sealing, a common sealing sheet isintroduced into mutually opposite grooves of adjacent foot plates.

The massive construction of the edge region in which the groove for thesealing sheet is arranged presents problems in terms of the thermal loadon the foot plate. On account of the high temperatures in the turbine,the foot plates are normally cooled by way of a coolant. In this case,special cooling measures have to be taken for the massive edge region,so as not to give rise to any excessive thermal stresses between themassive edge region and the relatively thin plate region of the footplate.

This problem is aggravated when a closed cooling circuit, for example aclosed steam cooling circuit, is provided for cooling, since this doesaway with the possibility of guiding through the massive edge regioncooling bores through which, for example, cooling air can flow. Instead,in the case of a closed cooling circuit, such bores have to be producedas blind holes, the cooling effect naturally being low in this case,since the cooling medium will scarcely flow through the blind hole to asufficient extent.

In a further seal variant, the grooves and the sealing sheet are setback from the hot-gas side located on the gas-space side and an undercutis introduced into the massive edge region below the sealing element.Here, too, there is then again the problem of the coolant flowingthrough this undercut to a sufficient extent. A third seal variant,according to which cooling ducts are introduced into the body of thefoot plate itself, is complicated in production terms.

In particular, here, there is the problem that, in order to form thecooling ducts during the casting of the foot plate, a core which ispositioned via spacers, also has to be cast in. The core and the spacersare removed by way of suitable measures after casting, so that thecavities formed thereby can be used as cooling ducts. However, there isa connection of the cooling ducts to the outside via the cavity producedby the spacers, so that a closed cooling circuit can be implemented onlywith difficulty.

SUMMARY OF THE INVENTION

An object on which an embodiment of the invention may be based is, in aturbine, to design the seal between adjacent guide vanes suitably forsimple cooling.

An object may be achieved, according to an embodiment of the invention,by a turbine, in particular by a gas turbine, with a gas space and witha number of guide vanes which each have a foot plate and a vane leafextending radially from the foot plate into the gas space, a sealingelement with a reception region, into which the foot plates extend,being provided in each case between the foot plates of adjacent guidevanes.

The fundamental idea of this configuration is to be seen in the reversalof the conventional sealing principle, in which a sealing sheet isintroduced into corresponding grooves of the foot plates. To be precise,this necessarily requires a reinforcement of the edge of the foot platesin the groove region, thus ultimately leading to the cooling problems.In this case, in a reversal of this sealing principle, the sealing sheetis not inserted into the foot plates, but, instead, the foot plates areintroduced into the sealing element. This avoids the need for areinforcement of the edge region of the foot plate. Coolability istherefore simplified and the foot plate is cooled homogeneously in allregions, so that no thermal stresses occur.

In a preferred design, the sealing element is designed with an H-shapedcross section with two longitudinal limbs connected via a transverselimb, there being formed between the longitudinal limbs two receptionregions which are separated from the transverse limb and into which thefoot plates of adjacent guide vanes extend in each case. The sealingelement thus partially covers the adjacent foot plates with its twolongitudinal limbs, so that, in addition to the sealing property, thefoot plates are held by the sealing element.

In view of assembly requirements during the production of the turbine,the sealing element is arranged preferably between guide vanes adjacentto one another in the circumferential direction of the turbine.

According to a preferred refinement, the foot plates each have a sideedge bent away from the gas space, in particular radially outward, thesealing element being arranged between two side edges of adjacent guidevanes. The effective sealing height of the seal is thereby increased,without the plate thickness of the foot plate being increased. The twobent-away side edges of the foot plates in this case come to bear, inparticular, on the transverse limb of the H-shaped sealing element.

In order to achieve homogeneous cooling and consequently avoid thermalstresses, the side edge has substantially the same material thickness asthe remaining foot plate.

In order to prevent the sealing element from projecting into the gasspace, the front side of the foot plate, the front side being directedtoward the gas space, has, in the region of the sealing element, abearing surface which is set back from the gas space and on which thesealing element lies. Preferably, at the same time, the sealing elementis flush with the foot plate.

In an expedient refinement, there is, for cooling the sealing element, aflow path in the form of a leakage gap for air between the sealingelement and the foot plates. There is therefore no desire to haveabsolute leak-tightness, in order to keep low the thermal load in theregion of the sealing element and at the side edges of the foot plate.As a rule, the outside space around the gas space in a turbine is keptat a higher pressure than the gas space, so that air enters the gasspace from outside via the leakage gap and the outflow of hot gas fromthe gas space is avoided.

In a particularly advantageous embodiment, a closed cooling system,through which a coolant is capable of flowing, is arranged in the rearregion of the foot plates which faces away from the gas space, that isto say in the outside space. The coolant is in this case, in particular,steam. Alternatively, the coolant used is also a liquid, such as water,or another gas, such as air or hydrogen. Such a closed cooling systemallows an effective, directional and homogeneous cooling of the footplates and of the entire guide vanes.

Preferably, at the same time, the coolant is capable of flowing, inparticular directly, over the rear side of the foot plates which facesaway from the gas space, so that direct heat exchange takes placebetween the coolant and the foot plate.

In order to achieve an effective cooling of the foot plates, an inflowduct for the coolant is formed between an outer guide sheet and a bafflesheet, the baffle sheet being arranged between the outer guide sheet andthe foot plate and having flow orifices toward the foot plate, and areturn-flow duct for the cooling medium being formed between the bafflesheet and the foot plate. A closed cooling system, which has a highcooling action, is consequently implemented in a simple way. Duringoperation, the coolant is supplied via the inflow duct and is guided athigh velocity onto the foot plate via the, in particular, nozzle-likeflow orifices in the baffle sheet, so that intensive heat exchange takesplace between the coolant and the foot plate. The heated coolant issubsequently discharged in the return-flow duct.

Preferably, the baffle sheet is supported on the foot plate via asupporting element, so that the baffle sheet is held at a defineddistance from the foot plate.

For simple fastening, preferably the baffle sheet is fastened to thebent-away side edge of the foot plate and the guide sheet is fastened,in particular, to the baffle sheet.

In order to achieve a simple mounting of the foot plates and at the sametime good sealing of the foot plates both in the circumferentialdirection and in the axial direction between adjacent turbine stages,preferably the sealing element described is provided for sealing in thecircumferential direction and a further sealing element is provided forsealing in the axial direction. Depending on the direction, therefore,and particularly for assembly reasons, differently designed sealingelements are used.

The further sealing element connects the foot plates to one another in astaple-like manner, preferably on their rear sides facing away from thegas space. The essential advantage is in this case to be seen in thestaple-like configuration of the further sealing element which spans thetwo foot plates. The further sealing element is in this case designed tobe elastic, in particular in a plurality of directions, so that, underthermal expansions, it follows the foot plates, without opening up agap. The sealing by the further sealing element is therefore largelyunaffected by thermal expansions.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are explained in more detailbelow with reference to the drawings, in which, in each case in a highlydiagrammatical illustration,

FIG. 1 shows a turbine plant,

FIG. 2 shows the sealing region between two foot plates adjacent to oneanother in the circumferential direction of the turbine, in aconventional embodiment,

FIG. 3 shows the sealing region in a configuration according to anembodiment of the invention, and

FIG. 4 shows a seal provided, in particular, for foot plates arrangednext to one another in the axial direction of the turbine plant.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to FIG. 1 a turbine plant 2, in particular a gas turbine plantof a turbo set for a power station for energy generation, comprises acombustion chamber 4 and a turbine 6 which is arranged downstream of thecombustion chamber 4 in the longitudinal or axial direction 8 of theturbine plant 2. The turbine 6 is illustrated, cut away, in a partregion, so that it is possible to look into the gas space 12 of theturbine 6. The flow path of a hot gas HG through the turbine 6 isdesignated as the gas space 12.

During operation, the combustion chamber 4 is supplied via a gas supply14 with a fuel gas BG which is burnt in the combustion chamber 4 andwhich forms said hot gas HG. The hot gas HG flows through the turbine 6and leaves the latter as cold gas KG via a gas discharge line 16. Thehot gas HG is guided in the turbine 6 via guide vanes 18 and movingblades 20. In this case, a shaft 22, on which the moving blades 20 arearranged, is driven. The shaft 22 is connected to a generator 24 for thegeneration of electric energy.

The moving blades 20 extend radially outward from the shaft 22. Theguide vanes 18 have a foot plate 21 and a vane leaf 23 fastened to thelatter. The guide vanes 20 are fastened outwardly to the turbine 6 viatheir foot plate 21 in each case on what is known as a guide vanecarrier 26 and extend radially into the gas space 12. As seen in thelongitudinal direction 8, the guide vanes 18 and the moving blades 20engage one into the other in a tooth-like manner. A plurality of movingblades 20 and of guide vanes 18 are in each case combined to form aring, each guide vane ring representing a turbine stage.

In the exemplary embodiment of FIG. 1, the second turbine stage 28 andthe third turbine stage 30 are illustrated by way of example.

The foot plates 21 of the individual guide vanes 18 are contiguous toone another both in the axial direction 8 and in the circumferentialdirection 32 of the turbine 6 and outwardly delimit the gas space 12.

The foot plates 21 adjacent to one another are sealed relative to oneanother, in order to keep leakage gaps 34 between them as small aspossible.

According to a conventional seal variant for two foot plates 21 arrangednext to one another in the circumferential direction 32, the latter havea thickened edge region 36, as shown in FIG. 2. Grooves 40 which arelocated opposite one another and into which a common sealing sheet 42 isinserted are worked into the end faces 38 of the edge regions 36 ofadjacent foot plates 21. This sealing principle, according to which thefoot plates 21 receive a sealing element in the form of a sealing sheet42, necessarily requires the reinforced edge region 36. As a rule, thisedge region 36 has a thickness D1 higher by the factor 3 to the factor 5than the thickness D2 of the remaining foot plate 21.

These different material thicknesses in the edge region 36 and theremaining foot plate 21 lead to problems in terms of a uniform andhomogeneous cooling of the foot plates 21, so that there is a risk ofthermal stresses.

In order to avoid this problem, according to the proposed preferredembodiment shown in FIG. 3, the conventional sealing principle isreversed, so that, in this case, the foot plates 21 extend into asealing element 44. The sealing element 44 is designed with an H-shapedcross section and has two longitudinal limbs 46 which are connected toone another via a transverse limb 48.

The sealing element 44 is therefore designed in the manner of a“double-T girder”. Between the two longitudinal limbs 46 are formed tworeception regions 50 which are separated from the transverse limb 48 andinto which the foot plates 21 extend. Alternatively to the H-shapeddesign, the sealing element 44 has a T-shaped design, that is to saywith only one longitudinal limb 46. In a sealing element 44 of thiskind, the reception spaces formed are open.

In the region of the sealing element 44, the front sides 52 of the footplates 21, the front sides being oriented toward the gas space 12, eachhave a bearing surface 54 which is set back from the gas space 12 and onwhich one longitudinal limb 56 of the sealing element 44 lies. For thispurpose, the foot plate 21 has a step-shaped design in the region of thesealing element 44. The end regions of the foot plates 21, said endregions adjoining the step, are bent away outward from the gas space 12approximately perpendicularly and in each case form a bent-away orradially extending side edge 56. The side edges 56 of the adjacent footplates 21 directly fit snugly against the transverse limb 48. Anincrease in sealing height H is thereby achieved, without the foot plate21 being reinforced in the sealing region. A flow path 58 designed as aleakage gap is formed between the sealing element 44 and at least one ofthe foot plates 21, so that, for example, air from the outside space 60facing away from the gas space 12 can flow via the flow path 58 into thegas space 12 and therefore cools the sealing region, that is to say thesealing element 44 and the side edges 56.

To cool the foot plates 21, in particular, a closed cooling system 62 isprovided, which uses preferably steam as a coolant and a detail of whichis illustrated in FIG. 3. This closed cooling system 62 has an inflowduct 64 and a return-flow duct 66. The inflow duct 64 is formed betweenan outer guide sheet 68 and a baffle sheet 70 which is arranged betweenthe guide sheet 68 and the foot plate 21.

The baffle sheet 70 has flow orifices 72 which are designed in themanner of nozzles, so that the coolant supplied via the inflow duct 64flows over into the return-flow duct 66 along the arrows illustrated. Byvirtue of the nozzle-like operation of the flow orifices 72, the coolantis guided at high velocity against the rear side 74 of the foot plate21, so that effective heat transmission between the coolant and the footplate 21 is implemented.

In order to achieve a uniform action of the cooling system 62, thebaffle sheet 70 is supported against the foot plate 21 and kept at adistance from the latter via supporting elements 76, for example in theform of weld spots or welded webs. The baffle sheet 70 is directlyfastened, in particular welded, to the side edge 56 of the foot plate21, and the guide sheet 68 is fastened to the baffle sheet 70.

For assembly and cooling reasons, the sealing arrangement illustrated inFIG. 3 is provided, in particular, for two guide vanes 18 adjacent toone another in the circumferential direction 32. The illustrated inflowducts 64 and return-flow ducts 66 therefore extend in the axialdirection 8 of the turbine 6. The foot plates 21 of a guide vane ringare thus sealed relative to one another via the H-shaped sealing element44. For assembly reasons, this seal is less suitable, albeit possible inprinciple, for foot plates 21 of successive turbine stages 28, 30, saidfoot plates being adjacent to one another in the axial direction 8.

For the sealing of foot plates 21 adjoining one another in the axialdirection 8, according to FIG. 4 a further sealing element 80 ispreferably provided, which connects the foot plates 21 to one another ina staple-like manner on their rear sides 74. The further sealing element80 is in this case introduced and fastened in grooves 82 which extendessentially radially from the rear side 74 into the foot plates 21. Asillustrated in FIG. 4, the further sealing element 80 is, for example,of U-shaped design with two limbs 86 connected via an arc 84.

Alternatively to this, the further sealing element 80 is provided with awavy structure in the manner of a concertina. The elongate U-shapedconfiguration or else the configuration with the wavy structure has theeffect that the further sealing element 80 is elastic and allowsall-round movability of the foot plates 21 as a result of thermalexpansion. FIG. 4 also illustrates hooking elements 88 which arearranged on the rear sides 74 and by means of which the guide vanes 18are hooked into the guide vane carrier 26 (cf. FIG. 1).

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A turbine, comprising: a plurality of guidevanes, each including a foot plate and a vane leaf extending radiallyfrom the foot plate into a gas space; and a sealing element, including areception region into which the foot plates extend, wherein the sealingelement is provided between foot plates of adjacent guide vanes, whereinthe sealing element includes an H-shaped cross section with twolongitudinal limbs connected via a transverse limb, and includes tworeception regions, formed between the longitudinal limbs, which areseparated from the transverse limb and into which the foot plates ofadjacent guide vanes extend.
 2. The turbine as claimed in claim 1,wherein a closed cooling system, through which a coolant is capable offlowing, is arranged in the rear region of the foot plates which facesaway from the gas space.
 3. The turbine as claimed in claim 2, whereinthe coolant is capable of flowing over the rear side of the foot plateswhich faces away from the gas space.
 4. The turbine as claimed in claim3, wherein an inflow duct for the coolant is formed between an outerguide sheet and a baffle sheet arranged between the outer guide sheetand the foot plate and includes flow orifices toward the foot plate, areturn-flow duct for the cooling medium being formed between the bafflesheet and the foot plate.
 5. The turbine as claimed in claim 2, whereinan inflow duct for the coolant is formed between an outer guide sheetand a baffle sheet arranged between the outer guide sheet and the footplate and includes flow orifices toward the foot plate, a return-flowduct for the cooling medium being formed between the baffle sheet andthe foot plate.
 6. The turbine as claimed in claim 5, wherein the bafflesheet is supported on the foot plate via a supporting element.
 7. Theturbine as claimed in claim 5, wherein the baffle sheet is fastened to abent-away side edge of the foot plate and the guide sheet is fastened tothe baffle sheet.
 8. The turbine of claim 1, wherein the turbine is agas turbine.
 9. The turbine as claimed in claim 1, wherein the footplates each include a side edge bent away outwardly from the gas space,the sealing element being arranged between two side edges of adjacentguide vanes.
 10. The turbine as claimed in claim 9, wherein the sideedge has substantially the same material thickness as the remaining footplate.
 11. The turbine as claimed in claim 1, wherein the front side ofthe foot plate, directed toward the gas space, includes, in the regionof the sealing element, a bearing surface for the sealing element, saidbearing surface being set back from the gas space.
 12. The turbine asclaimed in claim 11, wherein the sealing element is flush with the footplate.
 13. The turbine as claimed in claim 1, wherein the sealingelement is arranged between foot plates adjacent to one another in thecircumferential direction, and wherein foot plates adjacent to oneanother in the axial direction, are assigned a further sealing elementwhich connects the foot plates to one another in a staple-like manner ontheir rear sides facing away from the gas space.
 14. A turbine,comprising: a plurality of guide vanes, each including a foot plate anda vane leaf extending radially from the foot plate into a gas space; anda sealing element, including a reception region into which the footplates extend, wherein the sealing element is provided between footplates of adjacent guide vanes, wherein the foot plates each include aside edge bent away outwardly from the gas space, the sealing elementbeing arranged between two side edges of adjacent guide vanes.
 15. Theturbine as claimed in claim 14, wherein the side edge has substantiallythe same material thickness as the remaining foot plate.
 16. The turbineas claimed in claim 14, wherein for cooling the sealing element, a flowpath for air is included between the sealing element and the footplates.
 17. The turbine as claimed in claim 14, wherein the sealingelement is arranged between foot plates adjacent to one another in thecircumferential direction, and wherein foot plates adjacent to oneanother in the axial direction, are assigned a further sealing elementwhich connects the foot plates to one another in a staple-like manner ontheir rear sides facing away from the gas space.
 18. A turbinecomprising: a plurality of guide vanes, each including a foot plate anda vane leaf extending radially from the foot plate into a gas space; anda sealing element, including a reception region into which the footplates extend, wherein the sealing element is provided between footplates of adjacent guide vanes, wherein the front side of the footplate, directed toward the gas space, includes, in the region of thesealing element, a bearing surface for the sealing element, said bearingsurface being set back from the gas space.
 19. The turbine as claimed inclaim 18, wherein the sealing element is arranged between guide vanesadjacent to one another in the circumferential direction of the turbine.20. The turbine as claimed in claim 18, wherein the sealing element isflush with the foot plate.
 21. A turbine, comprising: a plurality ofguide vanes, each including a foot plate and a vane leaf extendingradially from the foot plate into a gas space; and a sealing element,including a reception region into which the foot plates extend, whereinthe sealing element is provided between foot plates of adjacent guidevanes, wherein the sealing element includes an H-shaped cross sectionwith two longitudinal limbs connected via a transverse limb, andincludes two reception regions, formed between the longitudinal limbs,which are separated from the transverse limb and into which the footplates of adjacent guide vanes extend, and wherein the sealing elementis arranged between guide vanes adjacent to one another in thecircumferential direction of the turbine.
 22. A turbine, comprising: aplurality of guide vanes, each including a foot plate and a vane leafextending radially from the foot plate into a gas space; and a sealingelement, including a reception region into which the foot plates extend,wherein the sealing element is provided between foot plates of adjacentguide vanes, wherein the sealing element includes an H-shaped crosssection with two longitudinal limbs connected via a transverse limb, andincludes two reception regions, formed between the longitudinal limbs,which are separated from the transverse limb and into which the footplates of adjacent guide vanes extend, and wherein for cooling thesealing element, a flow path for air is included between the sealingelement and the foot plates.